Liposomal vitamin a and method of preparation

ABSTRACT

The invention relates to liposomal vitamin A and method of its preparing. The liposome containing vitamin A as active agent, carriers (supporter) and lipids as adjuvents and liposome-forming materials. The process comprises: adding vitamin A and lipids to carriers, forming a liposomal vitamin A in the form of solid, then rehydrating to give a liposomal dispersion. The process can improve the stability of vitamin A and liposomal vitamin A. The present liposome is useful for the manufacture of pharmaceutical and cosmetic formulation.

TECHNICAL FIELD

This invention relates to the field of pharmaceutical and cosmeticsproduction, mainly referring to a kind of Liposomes which containsVitamin A and the method of its preparation.

BACKGROUND OF THE INVENTION

Vitamin A is one of the essential nutriments of human body, which likesa hormone for the regulation of cell differentiation, growth anddevelopment and for the maintenance of metabolic balance and internalenvironment homeostasis, as well as for the maintenance of productiveability and vision in the dark. Vitamin A especially plays a key role onthe maintenance of the epithelia integrity and activation. Therefore, itcan promote the epithelia activation and keep skin bright and elastic.So Vitamin A was generally used as the biologically active ingredient incosmetics from domestic or international cosmetic companies.

But there are some defects of Vitamin A as a kind of dermal medicinesuch as instability due to many unsaturated double-bonds in its chemicalstructure, low permeability due to its great molecular weight, and theliposolubility by which Vitamin A should be packed in the hydrophiliccarrier for usage.

A characteristic of Liposome is its micro-vesicle structure which iscomposed of double lipid molecules. The microstructure can improve thestability of the sealed medicine, promote the endermic absorption,prolong the effect time, reduce side effects of the medicine, and hasthe ability to guide the medicine to the pathological areas. Therefore,Liposome was applied extensively to pharmaceutical and cosmeticsproduction. Vitamin A Liposomes can improve the stability of Vitamin A,promote the ability to permeate skin and the solubility in water. Now,Vitamin A Liposome, as well as the related cosmetics has already becomefocus of study.

It was by far reported that the Vitamin A Liposomes are all the commonLiposomes, namely, Liposomes Suspension. There are actually many defectsof the common Vitamin A Liposomes as follows.

1. The Liposomes Suspension as colloid solution lacks of thermodynamicstability. So it is easy for the Liposomes Suspension to conglomerate,amalgamate and sedimentate in the aqueous solution. In addition, due tothe oxidative cleavage, the leakage of the sealed medicine also causesthe instability of the common Liposomes.

2. The marked instability of the medicine containing Vitamin A in theaqueous solution is due to the structure instability of the Vitamin A.

3. The Vitamin A Liposome Suspension has commonly the fixed Vitamin Acontent. Furthermore, the different Vitamin A content is required fordifferent cosmetics production. So it is inconvenient to producecosmetics containing Vitamin A by using the Vitamin A LiposomesSuspension because of the definite proportion of Liposome in thecosmetics with Vitamin A.

Therefore, it is very important to seek for a new method by whichVitamin A Liposomes and the related medicine become stable for long-termpreservation and conveniently producing cosmetics with Vitamin A.

An object of the present invention is to provide a new kind of Vitamin ALiposomes, which not only improves the stability of Vitamin A andLiposome but also is more convenient for cosmetics production.

Another object of the present invention is to provide a new method ofVitamin A Liposome preparation.

SUMMARY OF THE INVENTION

The sealed Vitamin A serves essentially as biologically activeingredient in the new vitamin A Liposomes provided by this invention andwhich contains support substance and the lipid ingredients serving asthe accessories and the membranes.

The method of vitamin A Liposomes preparation is as follows. The solidVitamin A pro-Liposome is made from Vitamin A and the lipid ingredientsby adding the support substance. According to your needs, Vitamin ALiposomes can be obtained through hydration and vibration by addingwater into the Vitamin A pro-Liposomes before usage.

DETAILED DESCRIPTION OF THE INVENTION

This invention openly provides a new kind of Vitamin A Liposomes, whichnot only improve the stability of Vitamin A and Liposome but also ismore convenient for production of the cosmetics with the sound formula.

The vitamin A Liposomes produced through this invention contains vitaminA serving as its active ingredient, and the support substance and thelipid ingredients as the accessories and the membranes. In the Vitamin ALiposomes the content of vitamin A is 0.1-20%, and the support substance2-40%. The remainders are the lipid ingredients, buffer and water.

In the vitamin A Liposomes produced through this invention the supportsubstance is selected from one or several sorts of materials as follows:Mannitol, Sorbitol, Glucose, Sucrose, Lactose, Mycose, Sodium chloride,polyvinyl pyrrolidone, etc.

In the vitamin A Liposomes produced through this invention the lipidingredient is selected from one or several sorts of material as follows:Soya lecithin, Yolk lecithin, Distearoyl phosphatidyl choline,Dipalmitoyl Phosphatidyl Choline, Poloxamer, DimyristoylPhosphatidyl-choline, Ceramide, Nonionic Surfactant Brij, Cholesterol,etc.

This invention published the method of vitamin A Liposomes preparation.The solid Vitamin A pro-Liposome is made from Vitamin A and lipidingredients by adding the support substance. Then, Vitamin A Liposomescan be produced by adding water into the Vitamin A pro-Liposomes. TheVitamin A pro-Liposomes is a kind of the granular and dry solid agentwhich can be converted into the Vitamin A Liposomes through hydrationand vibration by adding water into the Vitamin A pro-Liposomes beforeusage.

The method of the Vitamin A pro-Liposomes preparation in this inventionis as follows:

(1) The lipid solution can be obtained when Vitamin A and the lipidingredients are melted by heating or dissolved by the organic solvent.

(2) The above-mentioned lipid solution is sprayed upon the supportsubstance suspending in the fluidized bed. The dry Vitamin Apro-Liposomes can be obtained after volatilization of the organicsolvent. In addition, the Vitamin A Liposomes with the support substancecan be also obtained from the lipid solution with Vitamin A and theaqueous solution with the support substance through the method of thefilm dispersion or Fusion or Filling. The Vitamin A pro-Liposomes can beobtained after the Vitamin A Liposomes is dehydrated by freeze-drying orSpray-drying.

In the Vitamin A pro-Liposomes the content of vitamin A is 0.2-40%. Thecontent of vitamin A is 0.1-20% in the Vitamin A Liposome which isobtained by adding water into the Vitamin A pro-Liposomes.

The proportion of the support substance is 1-80% in the Vitamin Apro-Liposomes, and 2-40% in the Vitamin A Liposomes.

Apart from these advantages of the common liposomes, such as improvingthe stability of Vitamin A, enhancing the endermic absorption,prolonging the effect time of drugs, the Vitamin A liposome producedthrough the method of the Vitamin A pro-liposomes preparation in thisinvention possesses advantages as follows:

1. Improving the stability of Vitamin A liposomes. Because thepro-liposome is solid, it has no defects of instability of the commonliposomes, such as conglomeration, sedimentation, amalgamation andleakage, etc. The Vitamin A pro-liposomes can be preserved for a longterm. Vitamin A liposomes can be obtained through hydration andvibration by adding water into the Vitamin A pro-Liposomes before usage.

2. Improving the stability of Vitamin A. The Vitamin A pro-liposomesproduced through this method is solid. The stability of the solidVitamin A serving as the active ingredient is greater than the liquidVitamin A.

3. Being mixed with other ingredients in the random proportion. It issimple and convenient to produce the cosmetics containing Vitamin A byusing the Vitamin A liposomes produced through this method as materiel.There is the definite range of Liposomes volume percentage in thecosmetics with liposomes. The property of cosmetics, such as viscosity,fluidity, consistance, the active ingredient content, etc, would beinfluenced out of the volume percentage range. It is inconvenient toproduce cosmetics containing Vitamin A by using the common Liposomesbecause of the definite volume percentage of Liposomes in the cosmeticswith liposomes. So the different Vitamin A content is required forproduction of the different cosmetics.

The liposomes with the different Vitamin A content can be obtained byusing the above-mentioned Vitamin A pro-liposomes through regulation ofthe added water volume before usage. The liposomes with the differentVitamin A content produced through this method can meet the differentdemands of the cosmetics formulas.

The experiment about the stability showed that the stability of theVitamin A pro-liposomes is more dependable as compared with the commonliposomes. Three groups of the Vitamin A pro-liposomes and the commonVitamin A liposomes were preserved in condition of 40 □ and 75% relativehumidity respectively. The Vitamin A contents of all samples weremeasured with high performance liquid chromatography respectively at 0,1, 2 and 3 months. The contents of Vitamin A in the Vitamin Apro-liposomes and the common Vitamin A liposomes at the 0 month servedas 100%. The content percentages were obtained when the contents at theother months were compared with the contents at the 0 month. The resultsshowed that the Vitamin A contents in the common Vitamin A liposomesgradually decreased with prolongation of the preservation time, but theVitamin A contents in the Vitamin A pro-liposomes only have a littlechange. Therefore, the Vitamin A pro-liposome has the ability to improvethe stability of Vitamin A serving as the active ingredient. TABLE 1Comparison of the stability of Vitamin A between in the pro-liposomesand in the common liposomes (n = 3) The content of Vitamin A (%) Time(Mon) 0 1 2 3 Common liposomes 100.00 90.24 87.12 76.33 Pro-liposomes100.00 99.98 100.05 97.80

The Vitamin A pro-liposomes produced through this method can be used inthe production of drugs and cosmetics containing Vitamin A.

THE PREFERRED EMBODIMENT

Our invention was illustrated with 3 examples as follows. Theseillustrations do not mean any restriction to this invention.

Example 1

Materials: Vitamin A 10 g, Lecithin of soybeans 30 g, Cholesterol 30 g,Poloxamer F₆₈ 40 g, Glucose 200 g, Chloroform 200 ml, Phosphoric acidbuffer (pH 7.4) 1000 ml.

Vitamin A, soy lecithin, poloxamer F₆₈ and cholesterol were put into around bottom flask (10 liter) and dissolved with chloroform, and thenthe flask was put into the constant temperature water bath (25-40° C.)for the Rotated Thin-Film Evaporation. A lipid membrane was obtained onthe bottom of the flask after evaporation and reserved for using.Glucose was dissolved with 800 ml Phosphoric acid buffer (pH 7.4), andthen the solution was filtered. The filtrate was poured into the flaskwith the lipid membrane. After hydration and vibration of the mixedsolution, Phosphoric acid buffer (pH 7.4) was added into the mixedsolution to 1000 ml. Liposomes Suspension was obtained through theultrasonic processing (output 4, duty cycle 50%, time 10 mins). Afterfreeze-drying (temperature −50 □, vacuity 20-100 millitorr), the looseVitamin A pro-liposome was obtained. Vitamin A Liposomes can be obtainedthrough vibration by adding the distilled water into the Vitamin Apro-Liposomes, according to your needs, before usage.

Example 2

Materials: Vitamin A 100 g, Yolk lecithin 50 g, Cholesterol 50 g,Sucrose 40 g, Phosphoric acid buffer (pH 7.4) 1000 ml.

Vitamin A, yolk lecithin, cholesterol were put into a Conical ErlenmeyerFlask and were melted by heating or dissolved with the organic solventThe flask with the lipid solution was put into the constant temperaturewater bath (80° C.) for using. Sucrose (40 g) was dissolved with 800 mlPhosphoric acid buffer (pH 7.4), and then the solution was filtered. Thefiltrate was heated to the same temperature as the lipid solution andmixed with the lipid solution through vibration. Phosphoric acid buffer(pH 7.4) was added into the mixed solution to 1000 ml afterrefrigeration of the mixed solution. Liposomes Suspension was obtainedthrough the high pressure homogenizing (the range of pressure, 50 MPa-10MPa). After the Spray-drying, the Vitamin A pro-liposomes with betterliquidity was obtained. Vitamin A Liposomes can be obtained throughvibration by adding the distilled water into the Vitamin Apro-Liposomes, according to your needs, before usage.

Example 3

Materials: Vitamin A 50 g, polydioxyethylene hexadecyl ether

60 g, Cholesterol 40 g, Poloxamer F₆₈ 50 g, Mycose 80 g, Ethyl ether 200ml, Phosphoric acid buffer (pH 7.4) 1000 ml.

Vitamin A, polydioxyethylene hexadecyl ether

poloxamer F68, cholesterol were put into a Conical Erlenmeyer flask (500ml) and dissolved with Ethyl ether for using. Mycose (80 g) wasdissolved with 800 ml Phosphoric acid buffer (pH 7.4), and then thesolution was filtered. The filtrate was poured into the flask with thelipid solution. After volatilization of organic solvent, LiposomesSuspension was obtained through the magic stirring (stirring speed,200-1000 rpm) in the constant temperature water bath (30˜60 □). Afterfreeze-drying (temperature −50 □, vacuity 20-100 millitorr), the looseVitamin A pro-liposome was obtained. Vitamin A Liposomes can be obtainedthrough vibration by adding the distilled water into the Vitamin Apro-Liposomes, according to your needs, before usage.

The above-mentioned examples are merely used to illustrate the preferredembodiment in our invention. Technicians in this field are allowed tomodify and change these methods, which does not depart from the spiritand range of this invention. The attached claims cover all of thosemodifications in the range of this invention.

1-6. (canceled)
 7. A Vitamin A liposome, comprising: Vitamin A servingas an active ingredient, and the support substance and the lipidingredients serving as the accessories and the membranes; characterizedin that: the content of Vitamin A is 0.1-20%, and the support substance2-40%, the remainders are the lipid ingredients, buffer and water. 8.The Vitamin A Liposome according to claim 7, wherein the supportsubstance is selected from one or several sorts of materials as follows:Mannitol, Sodium chloride, polyvinyl pyrrolidone, etc.
 9. The Vitamin ALiposome according to claim 7, wherein the lipid ingredient is selectedfrom one or several sorts of materials as follows: Yolk lecithin,Distearoylphosphatidyl choline, Dipalmitoyl Phosphatidyl Choline,Poloxamer, Dimyristoyl Phosphatidyl-choline, Nonionic Surfactant Brij,etc.
 10. A method of Vitamin A Liposomes preparation, characterized inthat: the solid Vitamin A pro-liposome is made from Vitamin A and thelipid ingredients by adding the support substance; according to yourneeds, the Vitamin A Liposomes can be obtained through hydration andvibration by adding water into the Vitamin A pro-Liposomes before usage.11. The method of Vitamin A Liposomes preparation according to claim 10,wherein the content of Vitamin A in the Vitamin A pro-Liposomes is0.2-40%, and the support substance 1-80%, the remainders are the lipidingredients.
 12. The method of Vitamin A Liposomes preparation accordingto claim 11, wherein the process of Vitamin A pro-Liposomes preparationis as follows: (1) The lipid solution can be obtained when Vitamin A andthe lipid ingredients are melted by heating or dissolved by the organicsolvent; and (2) The above-mentioned lipid solution is sprayed upon thesupport substance suspending in the fluidized bed, the dry Vitamin Apro-Liposomes can be obtained after volatilization of the organicsolvent; in addition, the Vitamin A Liposomes with the support substancecan be also obtained from the lipid solution with Vitamin A and theaqueous solution with the support substance through the method of thefilm dispersion or Fusion or Filling, the Vitamin A pro-Liposomes can beobtained after the Vitamin A Liposomes is dehydrated by freeze-drying orSpray-drying.